Charged penalty for their failure to deliver

On 26 August I paid 50% deposit for an order with Furniture Express. The lady was going to contact me once the order was ready so I can pay the 50% balance.

About 3 weeks later, i sent an inbox asking of status. I received no response. I contacted them again aaking if I could change to another cot, a more expensive one. This request was sent on email and on messenger. No one responded.

I eventually cancelled after their timeline to deliver had expired (timeline is 4-6 weeks, i cancelled at 6.5 weeks). Only then the outlet started calling me, and i asked for written response as I had procured a second hand cot to prepare the nursery. They advised that they will charge me 10% of the invoice value as handling fee, citing they did not deliver because of the part payment. This is absurd, why would anyone in their right mind throw more money into a black hole where no one responds to queries?

I tried to argue my case as i felt like I am being penalised for lack of communication and inability to deliver on their part.

I asked them to reconsider and give me full refund. The request was ignored for a further 15 days or so until I threatened to report them to MamaMagic.

I have received payment less the 10% of the invoice value which is just over R400.

I am failing to understand how this outlet can literally default on their terms, fail to communicate and compensate themselves for it. Its a win win for them and I as a customer have been *****ed over, disrespected, ignored and basically ****** in broad daylight?